TECHNICAL ARTICLES / RESOURCES
ELECTROLESS NICKEL PLATING
Electroless nickel plating, (as it name implies), is a nickel coating in fact an alloy coating containing approximately 10% phosphorous that is deposited by chemical reduction rather than electrolytically.
The coating has remarkable qualities:-
Excellent corrosion resistance.
Deposit uniformity, regardless of the shape of the item plated. Refer Fig 1 and Fig 2
High hardness, as plated 45 RC.
Heat treatable. Nickel phosphorous is a heat treatable alloy and a hardness figure up to 68 RC can be achieved.
Controllable deposit. Close tolerances can be maintained and the need for post plating grinding is eliminated.
Quality finish. Although classed as an engineering coating the deposit has a pleasing stainless steel appearance and is often used to give a product a quality lift.
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Coverage by electroplating is uneven, particularly at corners
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Coverage of electroless nickel is evenly distributed over total area regardless of shape
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Electroless nickel has found application in a broad range of industries :-
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General engineering.
Packaging / materials handling
Automotive.
Toolmaking
Aerospace
Electronics |
Petroleum and chemical industries
Food
Mining
Reclamation of worn parts
Military
Hydraulics / pneumatics |
The coating is often used as an alternative to stainless steel for cost and practicality reasons.
Summary of electroless nickel features:-
Excellent corrosion resistance, dependant upon coating thickness
Phosphorous content 9-11%.
Melting point 890deg C. (the deposit has poor hot hardness)
Adhesion to mild steel 30,000 - 60,000psi
Hardness as plated 45 RC
Hardness after heat treatment of 1 hour at 400degC 68 RC
Good solderability.
Specifications
There is no Australian standard for electroless nickel, however the process is covered by, US and UK specifications namely AMS 2404 (USA) and DEF Std 03-5 (UK). In an addition to this several manufacturers call up their own specification.
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